Handover control for networks with several types of backhaul connections

Abstract

There are provided measures for handover control for backhaul connections, said measures exemplarily including evaluation of the suitability of an access node cell in access network as target for a handover of a terminal based on delay information being indicative of an expected packet delay in a cell of the access node, wherein such delay information may be generated and/or exchanged in the access network. Said measures may exemplarily be applied for improving handover control in relay-enhanced access networks or networks that contain access nodes connected via different kinds of backhaul that can result in different end-to-end packet delays.

The invention claimed is: 
     
       1. A method comprising
 receiving delay information being indicative of an expected packet delay in a cell of an access node in an access network,
 wherein the delay information relates to backhaul resources, 
 wherein the backhaul resources are heterogeneous, 
 wherein the heterogeneous backhaul resources comprise at least one of the following:
 backhaul resources between base stations of different hierarchical level in terms of logical, structural, or both logical and structural network deployment, 
 backhaul resources between different types of base stations and the network, 
 backhaul resources differing in technology from the network, 
 backhaul resources differing in technology from a system using homogeneous backhaul technology, 
 backhaul resources differing in handover from one another, and 
 backhaul resources differing in connectivity from one another, where end-to-end delay characteristics vary depending on the choice of base station; 
 
 
 evaluating the suitability of the access node cell as target for a handover of a terminal based on the expected packet delay of the access node cell; and 
 enabling or disabling the access node cell as target for a handover of the terminal based on the evaluated suitability thereof. 
 
     
     
       2. The method according to  claim 1 , further comprising
 obtaining delay requirement information being indicative of a tolerable packet delay for the terminal, 
 wherein the evaluating is based on the expected packet delay of the access node cell and the tolerable packet delay for the terminal. 
 
     
     
       3. The method according to  claim 1 , further comprising
 receiving handover measurement reporting information being indicative of a signal quality in the cell of the access node for the terminal, 
 wherein the evaluating is based on the expected packet delay of the access node cell and the signal quality in the access node cell for the terminal. 
 
     
     
       4. The method according to  claim 1 , wherein
 the evaluating is made using predetermined relative weights of any one of the parameters on which the evaluation is based, and/or 
 the evaluating is made pre-emptively irrespective of a handover demand of the terminal and/or on demand with respect to a handover demand of the terminal. 
 
     
     
       5. The method according to  claim 1 , wherein
 the method further comprises determining the expected packet delay in the access node cell based on the received delay information, and/or 
 the delay information comprises one or more of 
 measurement information of an actual packet delay in the access node cell, 
 resource characteristic and/or resource usage information of the access node cell, 
 mobility characteristic information of the access node cell, and 
 multi-hopping characteristic information of the access node cell, 
 wherein the multi-hopping characteristic information of the access node cell may comprise 
 cumulative delay information, including delay information of the access node cell and any access nodes between the access node of the cell and its controlling access node, and/or 
 relay depth information, being indicative of a number of relay levels between the access node of the cell and its controlling access node, in case the access node of the cell is a relay node of a relay-enhanced access network. 
 
     
     
       6. The method according to  claim 1 , wherein
 the method is operable at or by a donor base station controlling one or more relay nodes in a relay-enhanced access network, wherein said access node of said cell is a relay node, or the method is operable at or by a relay node in a relay-enhanced access network, wherein said access node is another relay node than said relay node, and/or 
 the method is operable at or by a macro base station, wherein said access node of said cell is a femto/home base station, or the method is operable at or by a femto/home base station, wherein said access node is another femto/home base station than said femto/home base station, and/or 
 said access node and/or an apparatus performing the method is part of an evolved radio access network in accordance with LTE and/or LTE-Advanced specifications. 
 
     
     
       7. An apparatus comprising
 a receiver configured to receive delay information being indicative of an expected packet delay in a cell of an access node in an access network,
 wherein the delay information relates to backhaul resources, 
 wherein the backhaul resources are heterogeneous, 
 wherein the heterogeneous backhaul resources comprise at least one of the following:
 backhaul resources between base stations of different hierarchical level in terms of logical, structural, or both logical and structural network deployment, 
 backhaul resources between different types of base stations and the network, 
 backhaul resources differing in technology from the network, 
 backhaul resources differing in technology from a system using homogeneous backhaul technology, 
 backhaul resources differing in handover from one another, and 
 backhaul resources differing in connectivity from one another, where the end-to-end delay characteristics vary depending on the choice of the base station; 
 
 
 a processor configured to evaluate the suitability of the access node cell as target for a handover of a terminal based on the expected packet delay of the access node cell; and 
 enable or disable the access node cell as target for a handover of the terminal based on the evaluated suitability thereof. 
 
     
     
       8. The apparatus according to  claim 7 , wherein the processor is further configured to
 obtain delay requirement information being indicative of a tolerable packet delay for the terminal, and 
 evaluate based on the expected packet delay of the access node cell and the tolerable packet delay for the terminal. 
 
     
     
       9. The apparatus according to  claim 8 , wherein
 the processor is further configured to determine the tolerable packet delay for the terminal based on the received delay requirement information, and/or 
 the delay requirement information comprises one or more of 
 a number of active bearers of the terminal, 
 a type of the one or more active bearers of the terminal, and 
 a delay characteristic of the one or more active bearers of the terminal. 
 
     
     
       10. The apparatus according to  claim 7 , wherein
 the receiver is further configured to receive handover measurement reporting information being indicative of a signal quality in the access node cell for the terminal, and 
 the processor is further configured to evaluate based on the expected packet delay of the access node cell and the signal quality in the access node cell for the terminal. 
 
     
     
       11. The apparatus according to  claim 7 , wherein the processor is further configured to
 evaluate using predetermined relative weights of any one of the parameters on which the evaluation is based, and/or 
 evaluate pre-emptively irrespective of a handover demand of the terminal and/or on demand with respect to a handover demand of the terminal. 
 
     
     
       12. The apparatus according to  claim 7 , wherein the processor is further configured to
 instruct the terminal to start or stop handover measurement and/or handover measurement reporting for the access node cell, when the access node cell is enabled or disabled, respectively, and/or decide on a handover of the terminal to the access node cell, when the access node cell is enabled, based on the evaluated suitability thereof with respect to a suitability and/or existence of one or more other access node cells. 
 
     
     
       13. The apparatus according to  claim 7 , wherein
 the processor is further configured to determine the expected packet delay in the access node cell based on the received delay information, and/or 
 the delay information comprises one or more of measurement information of an actual packet delay in the access node cell, 
 resource characteristic and/or resource usage information of the access node cell, 
 mobility characteristic information of the access node cell, and 
 multi-hopping characteristic information of the access node cell, 
 wherein the multi-hopping characteristic information of the access node cell may comprise 
 cumulative delay information, including delay information of the access node cell and any access nodes between the access node of the cell and its controlling access node, and/or 
 relay depth information, being indicative of a number of relay levels between the access node of the cell and its controlling access node, in case the access node of the cell is a relay node of a relay-enhanced access network. 
 
     
     
       14. The apparatus according to  claim 7 , wherein
 the apparatus is operable as or at a donor base station controlling one or more relay nodes in a relay-enhanced access network, wherein said access node of said cell is a relay node, or the apparatus is operable as or at a relay node in a relay-enhanced access network, wherein said access node is another relay node than said relay node, and/or 
 the apparatus is operable as or at a femto/home base station, and/or 
 the apparatus is operable as or at a macro base station, wherein said access node of said cell is a femto/home base stations, or the method is operable at or by a femto/home base stations, wherein said access node is another femto/home base stations than said femto/home base stations, and/or 
 said access node and/or said apparatus is part of an evolved radio access network in accordance with LTE and/or LTE-Advanced specifications. 
 
     
     
       15. An apparatus comprising
 a processor configured to generate delay information being indicative of an expected packet delay in a cell of a access node in an access network,
 wherein the delay information relates to backhaul resources, 
 wherein the backhaul resources are heterogeneous, 
 wherein the heterogeneous backhaul resources comprise at least one of the following:
 backhaul resources between base stations of different hierarchical level in terms of logical, structural, or both logical and structural network deployment, 
 backhaul resources between different types of base stations and the network, 
 backhaul resources differing in technology from the network, 
 backhaul resources differing in technology from a system using homogeneous backhaul technology, 
 backhaul resources differing in handover from one another, and 
 backhaul resources differing in connectivity from one another, where the end-to-end delay characteristics vary depending on the choice of the base station; and 
 
 
 a transmitter configured to transmit the generated delay information towards an apparatus in charge of evaluating the suitability of the access node cell as target for a handover of a terminal and configured to enable or disable the access node cell as target for a handover of the terminal based on the evaluated suitability thereof. 
 
     
     
       16. The apparatus according to  claim 15 , wherein
 the processor is further configured to measure an actual packet delay in the access node cell and to include corresponding information in the delay information, and/or 
 the processor is further configured to obtain a resource characteristic and/or a resource usage of the access node cell and to include corresponding information in the delay information, and/or 
 the processor is further configured to obtain a mobility characteristic of the access node cell and to include corresponding information in the delay information, and/or 
 the processor is further configured to obtain a multi-hopping characteristic of the access node cell and to include corresponding information in the delay information, 
 wherein the processor, to obtain the multi-hopping characteristic of the access node cell, may be further configured to 
 calculate a cumulative delay of the access node cell, including delay information of the access node and any access nodes between the access node of the cell and its controlling access node, and/or 
 specify a relay depth of the access node, being indicative of a number of relay levels between the access node of the cell and its controlling access node, in case the access node of the cell is a relay node of a relay-enhanced access network. 
 
     
     
       17. The apparatus according to  claim 15 , further comprising
 a receiver configured to receive a handover request for a handover of the terminal to the access node cell, 
 wherein the processor is further configured to perform admission control for the handover of the terminal to the access node cell based on the expected packet delay of the access node cell, or to delegate another access node to perform admission control for the handover of the terminal to the access node cell based on the expected packet delay of the access node cell on behalf of said access node. 
 
     
     
       18. The apparatus according to  claim 15 , wherein
 the apparatus is operable as or at the access node, and/or 
 said access node is a relay node in a relay-enhanced access network, and/or 
 said apparatus in charge of evaluating the suitability of the access node is a donor base station controlling one or more relay nodes in a relay-enhanced access network, wherein said access node of said cell is a relay node, or the said apparatus in charge of evaluating the suitability of the access node is operable at or by a relay node in a relay-enhanced access network, wherein said access node is another relay node than such relay node, and/or 
 said access node is a femto/home base station, and/or 
 said apparatus in charge of evaluating the suitability of the access node is a macro base station, wherein said access node of said cell is a femto/home base station, or the said apparatus in charge of evaluating the suitability of the access node is operable at or by a femto/home base station, wherein said access node is another femto/home base station than such femto/home base station, and/or 
 said access node and/or said apparatus in charge of evaluating the suitability of the access node and/or said apparatus is part of an evolved radio access network in accordance with LTE and/or LTE-Advanced specifications.